AFCI Testers by Nick Gromicko and Kenton Shepard What are AFCIs?   Arc-fault circuit interrupters (AFCIs) are special types of electrical receptacles (or outlets) and circuit breakers designed to detect and respond to potentially dangerous electrical arcs in home branch wiring. What are AFCI testers or indicators?   AFCI tester indicators (sometimes called AFCI testers) are portable